1. Field of the Invention
The present invention relates to the field of endoscope optics.
2. Description of Related Art
Endoscope optic fibers are used to illuminate the field of view. The fibers exhibit a very wide angle of radiation but their beam direction should be central to the field of view as much as possible. Fibers deviating in their directions of radiations entail brightness variations in the field of view. These fibers are bonded in the distal end zone for sealing purposes and to secure their attitudes which were set during assembly.
As regards straight-forward looking endoscope optics (extraneous to the species of the present application), all fibers are mounted parallel to the outer tube axis and terminate in an end face which is perpendicular to said axis. In this design their illuminations are all precisely in the viewing direction—hereafter line of sight.
Construction of optics with oblique lines of sight, wherein the objective lens is downward, is more difficult.
As regards a known endoscope optics of the applicant, which however is extraneous to the species of the present application, all fibers in a fiber bundle are configured above the fiber tube. On account of chamfering downward the inside of the outer tube and by using the same chamfer at the front end zone of the fiber tube, all fibers in the end zone are redirected downward in the direction of the line of sight. However the unilateral configuration of the fiber ends relative to the axis of viewing entails unsatisfactory illumination.
Illumination may be improved using bundle portions mounted on the side of the fiber tube. This design has been made known by STORZ Co. Therein the fiber tube is displaced downward relative to the outer tube. Until far to the rear, the region above the fiber tube and to the side of it is now filled with fibers. Above the fiber tube and starting at the end face, a horizontal wedge is driven into the fibers and it separates a middle, upper bundle portion from two lateral bundle portions, this wedge action forcing said lateral bundle portions downward along the line of sight.
All the above designs require not only aligning the fibers in the line of sight but also that they be mutually parallel. The fibers are configured proximally from the endoscope optics' end zone within a relatively large cross-sectional area between the tubes, said cross-sectional area being required to exceed the total cross-sectional area of the fibers. In this manner it is easier to insert the fibers during assembly. However these fibers also must be compressed in their distal end zones near the end face in order to attain mutual parallelism. This step is implemented in the initially cited design of the applicant by means of the two chamfers at the outer tube and the fiber tube, said chamfers—after the fibers have been installed, and upon advancing the fiber tube distally relative to the outer tube—then constricting the free cross-sectional area between themselves. In the STORZ design, the constriction is implemented by wedge action.
To-date an optimal design solution could not be found in the state of the art. Applicant's known design does in fact allow compressing the fibers well and thus attains good parallelism, but it only does permit this feature within the upper region of the endoscope optics. The STORZ design allows good overall illumination using lateral bundle portions reaching far down, though at less satisfactory compression which is implemented solely by wedging. As a result the fibers are less parallel to each other.